#include <stdio.h>
    #include <stdlib.h>

    int main(void)
    {
        printf("PATH=%s\n", getenv("PATH"));
        setenv("PATH", "hello", 1);
        printf("PATH=%s\n", getenv("PATH"));
    #if 0
        printf("PATH=%s\n", getenv("PATH"));
        setenv("PATH", "hellohello", 0);
        printf("PATH=%s\n", getenv("PATH"));


        printf("MY_VER=%s\n", getenv("MY_VER"));
        setenv("MY_VER", "1.1", 0);
        printf("MY_VER=%s\n", getenv("MY_VER"));
    #endif
        return 0;
    }